Purpose -This paper seeks to introduce a model of the initiation process in negotiations, and to describe a study of the effects of culture and personality on propensity to initiate and assertiveness in negotiations. Design/methodology/approach -Using a survey research approach and hierarchical regression analyses, initiation propensity and assertiveness were regressed against two country cultures diverse with respect to perceived appropriateness of initiation (Brazil and the USA) and four measures of personality (self-efficacy, locus of control, risk propensity, Machiavellianism). Findings -Regression analyses found three personality factors (risk propensity, self-efficacy, Machiavellianism) to be most significantly associated with initiation propensity/assertiveness, along with an interaction effect involving country culture and risk propensity. Research limitations/implications -Future studies might benefit from a broader, more diverse subject pool (beyond the two countries studied). This would allow for separate analyses of cultural dimensions, rather than treating culture as a composite measure. In addition, future research might include measures of actual initiation behavior. Practical implications -Initiation is a manageable process. Self-efficacy, for example, can be improved by observing others skilled in the initiation process, and through practicing initiation under more favorable conditions. Furthermore, an individual can follow a graduated approach to gain initiation confidence, beginning with simply engaging (without asking) and progressing to asking and optimizing. Originality/value -This paper offers a model for understanding the dynamics of the initiation process in negotiations, which generally has been overlooked by negotiation researchers. The study examines two sets of factors that can influence initiation behavior that have not been investigated in total -culture and personality.